Protonation of Zwitterionic Manganese and Rhenium Phosphoniostyryl Complexes (η 5 ‐C 5 H 5 )(CO) 2 M – –C( + PR 3 )=C(H)Ph: Experimental and DFT Study

Autor: E. S. Taits, Dmitry A. Valyaev, Ivan V. Glukhov, Nikolai A. Ustynyuk, Andrei M. Mazhuga, Vasily V. Krivykh, Pavel V. Petrovskii, Oleg V. Semeikin, Ivan A. Godovikov, Kamil I. Utegenov
Rok vydání: 2010
Předmět:
Zdroj: European Journal of Inorganic Chemistry. 2011:201-211
ISSN: 1099-0682
1434-1948
Popis: Stereoselective addition of tertiary phosphanes to manganese and rhenium phenylvinylidenes (η5-C5H5)(CO)2M=C=C(H)Ph (1 M = Mn; 2 M = Re) gave the corresponding zwitterionic Z-phosphoniostyryl adducts (η5-C5H5)(CO)2M−−C(+PR3)=C(H)Ph (3 M = Mn, PR3 = PPh2Me; 4 Mn, PPhMe2; 5 Mn, PMe3; 6 Re, PPh2Me; 7 Re, PMe3). Protonation of 3–7 with HBF4·OEt2 resulted in the formation of the η2-phosponioalkene complexes (η5-C5H5)(CO)2M(η2-E-HC(+PR3)=C(H)Ph) (8 Mn, PPh2Me; 9 Mn, PPhMe2; 10 Mn, PMe3; 11 Re, PPh2Me; 12 Re, PMe3) rather than in the corresponding phosphoniocarbene complexes (η5-C5H5)(CO)2M=C(+PR3)CH2Ph. It was shown by DFT calculations (B3LYP/6-31G*) that the protonation of 5 proceeds at the metal atom followed by C,H-reductive elimination in the intermediate hydride cis-(η5-C5H5)(CO)2(H)Mn−C(+PMe3)=C(H)Ph (14) to form the agostic complex (η5-C5H5)(CO)2Mn{η2-H–C(+PMe3)=C(H)Ph} (15) and subsequent isomerization of the latter into the final η2-phosphonioalkene 10. In line with the theoretical data, the low-temperature protonation (–80°C) of 3 with triflic acid in an NMR tube directly gave the corresponding phosponioalkene complex 8. Unlike 3, the protonation of their rhenium analogues 6 and 7 under the same conditions revealed the quantitative formation of cis-hydride intermediates cis-[(η5-C5H5)(CO)2(H)Re−C(+PR3)=C(H)Ph]OTf (16, 17), which undergo conversion into the corresponding η2-phosponioalkene complexes 11 and 12 at ca. –30°C
Databáze: OpenAIRE
Externí odkaz: